1. Field of the Invention
The present invention relates to a liquid crystal panel substrate having a fine pitch electrode structure, a method of manufacturing the substrate, a liquid crystal device created using the substrate and an electronic apparatus that includes the liquid crystal device.
2. Description of Related Art
In recent years, liquid crystal devices have become utilized widely as the displays of portable electronic apparatuses such as portable telephones, electronic notepads, and the like. This is largely due to the characteristic of liquid crystal devices as having low power consumption. Thus, conventional liquid crystal devices have little display capacity and are used to display characters and segments. However, because of increases in memory capacity and improvements in data communication technology, a demand has arisen for liquid crystal displays having greater display capacities. Because of this, many dot matrix type liquid crystal devices capable of large-volume display including graphics also have come to be used.
An indispensable quality control matter in the manufacture of such a dot matrix type liquid crystal device is the testing at the appropriate time for shorts or breaks among the display electrodes, and sending down the manufacturing process the substrate components assured by that testing to be good. A conventional method of testing for shorts and breaks of display electrodes is disclosed in Japanese Laid-Open Patent No. 59-042583. Namely, when testing electrodes of a translucent electrode pattern, shorts and breaks are detected electrically by printing voltage, for example direct current voltage, on the translucent electrode pattern, and by detecting the voltage taken by the various electrodes by contacting a short needle (a probe) to the surfaces of the translucent electrodes and moving the probe at a constant velocity.
FIG. 10 shows one example of an electrode arrangement of a conventional liquid crystal panel substrate and an electrode test method. Specifically, FIG. 10 shows that when the terminal for making a connection with an external circuit, i.e., external connection terminal 51, is electrically isolated from external electrode 52, testing probe 54 is contacted to one of multiple electrodes 53, and voltage, for example direct current voltage, is printed. Furthermore, a separate testing probe 56 is contacted to the end of an electrode on the opposite side of terminal 51 on electrode 53. The change in voltage is detected between probe 54 and probe 56. Another testing probe 57 is also contacted to the neighboring electrode 53, and the change in voltage is detected between probe 56 and probe 57.
FIG. 11 shows that a change in voltage is detected by moving probe 54 and probe 56 among the multiple electrodes as shown by arrow A while being connected to the same electrode, and reading the voltage by probe 54 during that movement. There is no electrical break in electrode 53 between probe 54 and probe 56 when the voltage detected by probe 54 is high (Vh). Thus, electrode breaks can be detected by probe 54 and probe 56.
On the other hand, the presence or absence of shorts between the neighboring electrodes 53 and 53 can be detected by moving probe 56 and probe 57 among the multiple electrodes as shown by the arrow A while being connected to neighboring electrodes, and reading the voltage by probe 57 during that movement. The voltage detected by probe 57 is always 0 if there is no short between those electrodes. However, a voltage is detected if there is a short between those electrodes. Thus, detecting electrode breaks and shorts between electrodes as described above, assures that electronic components having no defects are sent to the next process.
FIG. 12 shows another example of an electrode arrangement of a conventional crystal panel substrate and electrode test method. This method is used when every other electrode 53 is connected purposefully to external electrode 52, i.e., when they are shorted. Testing probe 54 is connected to external electrode 52, voltage, for example direct current voltage, is printed and another testing probe 56 is connected to a terminal end on the opposite side of external connection terminal 51 in the same manner as shown in FIG. 10. Furthermore, probe 56 is moved among the multiple electrodes as shown by arrow A, the difference in potential is detected by probe 56, and shorts between electrodes and electrode breaks are detected based on the difference in potential.
When the multiple electrodes 53 are normal, both the high voltage Vh and the low voltage V1 alternate as shown in FIG. 13. Also, when there is a break in the connection between electrode 53 and external electrode 52, there is no voltage peak for the electrode that should be high voltage Vh, i.e., the location of electrode number 3 shown in FIG. 14. Also, when there is a short between two neighboring electrodes 53 and 53, high voltage is detected in succession, as shown in FIG. 15. Thus, this conventional method uses the presence or absence of voltage printing alternates for every other electrode, to detect electrode breaks shorting with an external electrode and shorts between electrodes by moving one probe.
Because of restrictions of mechanical precision, limitations exist as to how small the cross-sectional area of the tip of the testing probe can be formed. Also, as shown microscopically, the tip of the probe contacts an electrode of the liquid crystal panel face. As a result, there was a problem that, in either of the above-mentioned testing methods, as the inter-electrode gap becomes smaller, the tip of the probe may straddle the gap and contact two adjacent electrodes. If this problem occurs in the conventional apparatus and method shown in FIG. 10, in which all the electrodes are electrically independent from the external electrode, both probe 56 and probe 57 may straddle a single electrode 53 and contact each other. Thus, probe 57 will always receive voltage, which will be misinterpreted as the existence of a short between the electrodes even when there is no short, and a correct determination is impossible.
Also, in the conventional apparatus and method shown in FIG. 12, in which every other electrode of the multiple electrodes 53 is in contact with external electrode 52, when the contact region of probe 56 is larger than the gap of the neighboring electrodes, probe 56 always receives high voltage and a correct determination is likewise impossible. Also, when it is determined that there is a short between electrodes, given the appearance of high voltage Vh in a location of low voltage Vl, it becomes impossible to detect the low voltage Vl region necessary to detect this short if the contact region of probe 56 is large. Thus, the problem exists that if there really is a short, it will be impossible to detect.
Consequently, the conventional testing methods shown in FIGS. 10 and 12, have the limitation that the inter-electrode interval must be at least 20 .mu.m at an inter-electrode pitch of at least 250 .mu.m. However, in recent years, the level demanded for liquid crystal devices is narrower than such a limit. For example, an inter-electrode gap of as little as 10 .mu.m at an inter-electrode pitch of as little as 180 .mu.m is being investigated.